Is there a way to have two knobs somehow inversely connected, so that when one is at max, the other is at min, and vice versa?
You can take the CV from a knob and compute (1-x) to get a CV that varies in reverse. If you pose a specific (small) example, someone could suggest how to produce the result you seek.
You can also just have only one knob, but reverse the influence they have on their targets.
What kind of knobs (Drambo internal knob module? Knobs on other modules? External hardware knobs?
You can use negative and positive modulation on any knob with a modulation input.
You could also assign a Morph Knob to the two knobs and make the first assign to knob minimum and the second assign to knob maximum, even if the knobs do not have a mod input.
When turning the Morph Knob, the two knobs will turn counter-clockwise. It will also, like when using positive/negative modulations as suggested above, allow for different amounts (like turn knob 1 by 100% and knob 2 by only 60%).